Telephone-exchange system.



' B. G.,DUNHAM.

TELEPHONE EXCHANGE SYSTEM APRLICATIQN FILED OCT- 5. 19(5.

1,262,3 1 5. I Patnted Apr. 9, 191&

56H" G. Dun/7am.

. Z '0 all whom it may] concern:

ED erAr s PATENT r c] BERT s. DUNHAN, OF HAWTHORNE, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGNMENTS, ro WESTERN ELECTRIC COMPANY, INcoEroRArEn, A CORPDRATION on NEW YORK.

'rELEr o N'E- XcHANeE SYSTEM.

Specification of Letters Patent. Patented Apt-9, 1918.

Application filed. October 5 1915. Serial 'No; 54,148.

Be it known that I, BERT GJDUNHAM, a citizen of the United States, residing at Hawthorne, in the county of Passaic and State of New Jersey, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems and has to do more particularly with a test or control circuit for telephone exchange systems utilizing automatic switches to extend the desired connection. The object of the invention is to provide effective and simplified means associated with the lines and switches for testingthe lines at a single test contact on each switch for each line.

In automatic switches of the character referred to, there is usually acircuit known as a test circuit thereof, including a test brush on the movable portion of such switch which tests on the one hand the calling or non-calling condition of the line, or, on the other hand, the busy or idle condition of the line, depending upon whether such automatic switch is a line finder switch or a connector switch.

According to one feature of the invention, a source of current is normally connected, through the line cut-off relay of each subscribers line, to multiply connected calling and called test terminals thereof, adapted to cause energization of the cut-off relay upon selection of the line by either a line finder or a connector switch over a circuit including any one of said test terminals.

Another feature of the invention resides in the means for decreasing the resistance of the test circuit of each subscribers. line whereby, responsive to a call. over any one of the subscribers lines, the potential of the test terminals of such line is increased sufficiently to render the line selectable by the line finders.

Another feature of the invention resides in the means employed for energizing the cut-of relays of the lines responsive to their selection by the line finders, together with the means employed for simultaneously therewith rendering a selected line unselectable by-either a line finder or a connector.

Other novel and useful features of the inra i s wi l ore ful y epi ari @113 following detailed description and appended claims.

Referring now to the drawing, for the purpose of simplifying the disclosure a plurality of battery symbols are illustrated. It is to be understood, however, that a single battery only need be'employed'. Therefore, it is to be assumed that each battery, symbol represents one and the same battery, and will be designated in the description fol-v lowing as battery B. For the purpose of stillfurther simplifying the disclosure, the circuits necessary to illustrate the invention only are shown, which includes a substation C, of a well-known arrangement, connected j with its line circuit D which islocated at the finders. These 100 sets of contactsare further divided into ten subgroups of ten contact sets each, so that in the operation of the switch E the sets of its brushes 18, 19,20 are first operated to the position corresponding to the subgroup of contacts containing the terminals of a calling line, and thereafter operated to cause the set of brushes, corresponding to the selected subgroup, to

select the desired terminals of the selected subgroup. V

In order to control the selection of the group of terminals containing the terminals of a calling line, eachline finder is provided with a set'of group contact terminals central ofiice, circuits of a line finder E'and terminal sets 8, 9, 10 of the associated line' 21 and a cooperating brush 22, there being as many group contacts 21 as'there are subgroups of sets of contacts 8. 9, 10, of which, of course, there are ten. 5 Therefore, it W111 be seen that each group of 100 lines is furtherdivided into ten. subgroups of tenlines each. For eachsubgroup of ten lines a group relay, GBC is provided,being common to it tens line circuits D and connected by a conductor 25'to its correspond ng group te c ntact .21.v i.. 1 i.

.113. Each of the connector switches is provided with a set of cooperating brushes for each subgroup,adapted to be rotated to the position With the corresponding set of brushes in the position to be thereafter ro- Q tated into and out of connection with the terminals 111, 112, 113 of the selectedsul ,groupto engagement with the set of terminals pf a desired line. Y

The ,type of line finder and connector switches of-the circuits illustrated are pro.- *vided with a set of three brushesfor ea-ch su-bg-roup of terminals spirally arranged corresponding upon carrier (not shown) ,adapted'to be rotated step by step, responsive to energizat ons-and deenergizations ofa heremtermed .rotary magnet, to the position corresponding to the-sub 'roua inwhich a 'set-of-terminals b ,o fadesired line is included, and thereafter ,theset of brushes, corresponding to thesubgroup of the desired line, s rntatedstep by jstep, responsive to energizationsand deenergizations of afherein termed vertical magnet, into and out of connection with the sets of Contact terminals of the lines of the selected subgroups until the set connected with the desired line is engaged. Thereafter, at the time of disconnection, the brushes are restored to their normal posi- =tion,.responsive.tothe energization of a releasemag-net associated withand individual to each of the switches. In addition, each switch is also provided with what is comm only termed aside switch, which comprises a plurality of brushes each adapted to .be positioned to connectionsuccessively with a plurality of associated passive contacts. The side switch of each of the line finders is provided with fivezbrushes, each adapted to be adjusted successively .topcsitions l, 2 and '3 into engagement with passive contacts corresponding thereto.

Considering now the operation of the illustrated arrangement, subscriber at sidestaticn'O, desiring toinitiate acall, removes the receiver rfrom the switchhook, estaldishing an energizing circuit for line relay from grounded battery B,:left-hand winding of relay LR, outer contact of cutoff relay CO, line conductor 6, through the substation, returning overthe line conductorl', .innencontact of relay CO, right-hand winding of relay LR to ground, whichenergizes the relay LR, establishing circuit for the group relay GBC from ground, winding of GBC, contact or relav 1GB, winding of resistance coil 11, battery'B to ground, and in multiple therewith through winding of CO, battery at ground. CO; is not energized, due to the re sistance of the relay G BG in series. Also the connection of the winding of resistance coil 11 and battery I) in 'multiple aviththe winding of the cut-oil relay 1C0 increases the potential of the test contact 8 upon connection therewith of the brush 20 of the line finder.

The energization of relay GBC establishes circuit viior the,sideswitch magnet SSM from ground, alternate contact of GBC, side switch arm 16,-its engaged normal contact,

normal contact 21, brush ,22 in. engagement therew th, lett-hand contact of test relay Kilt, winding ot side switch magnet SSltl, la ttery-B to ground, and in mult ple therewith ,circuit Sror the slow release control relays 23 of tech of the line finders of the group frog-n ground, alternate contact of {S BC, cent-act or release magnet REL, windng of slow release -relay 23, "battery :13 to ground, which energizes the magnet SSM and relays -23, establishing circuit for the flow-ofcurrent a ron conductor 24., grounded at the first selector switch (not .sliown).

unless the line ofthe callingsubstation be included in the subgroup corresponding to the first contact 21 from normal,established from ground, normal contact of relay'GBC of the subgroup corresponding to the first contact- 21- from iormah-thence over common conductor-25 to first contact21 from normal, brush 2:2 now in engagement therewitlnlefthand contact of lR, winding oi $5.5M, battery "B to g1OLl11Cl, '11Cl1 holds magnet SSM in its energized position and maintains the traced vibratory circuit for the magnet RM, which is again energized and the sets of brushes 18 to 20 inclusive rotated to the position corresponding to the second subgroup, and the brush 22 to connection-with the second contactQL-from normal, whereupon a substitute circuit for the magnet SSM is, unless the line of the calling substat on be ncluded in the second subgroup,

established, which includes normal contact of the relay GBC of the subgroup, second Contact :21 from normal, and so on untilthe brush 22 en-gages Contact '21 corresponding to a 'subgroup i-n which is include'dthe lii'ie of a calling substation awaiting selection, when, owingto the then energized condition of the corresponding relay GBC, circuit for the magnet SSM is interrupted and themagnet denergiz ed, interrupting circuit for the magnet RM, thereby preventing its further energization. i l

Assuming the line of the substation C to be included in the subgroup corresponding to the first contact 21from normal, then, upon disconnection of the brush 22 from its normal contact, owing to the energized'condition of the corresponding relay GBC, circuit for the magnet SSM is interrupted, the magnet deenergized, which, by the opening of its contact, interrupts circuit for the magnet BM, preventing further rotation of the brushes, whereby the set of brushes 18 to 20, inclusive, corresponding to the first subgroup,vare left in position to be moved into connection with the set of contacts 8 to 10, inclusive, of the lines of the first subgroup. The deenergization of magnet SSM causes the rotation of the side switch brushes 13 to 17, inclusive, from connectionwith their associated normal contacts to. connection with their associated first contacts from normal, which, by the interruption of brush 17:trom its normal contact, disconnects magnet RM, and by the connection of brushes 15 and 16 with their first contacts from normal connects the winding of relayTR with the brushes 20 and establishes circuit for the magnet SSM from ground, alternate contact of relay GBC, brush 16, I its engaged first contact from normal left-hand contact of TR, winding of SSM, battery B to ground, which energizes the magnet SSM and establishes a vibratory circuit for the magnet VM from conductor 24, grounded at the first selector switch, alternate contact of relay 23, contact of SSM, right-hand contact of TR, interrupter contact of RM, interrupter contact of VM, brush 17, its engaged first contact' from normal, winding of VM, battery B 'to ground, which energizes and moves the brushes 18 to 20, inclusive, corresponding to the selected subgroup, into engagement with the first set of contacts 8, 9, 10, multi- 7 ply connected terminals of the first line of the selected subgroup;whereupon, if such line be a calling line and awaiting selection, circuit for the flow of current 'suiiicient to energize the relay TB is established from ground, winding of TR, first side switch contact from normal, brush 15 in engage menttherewith, brush 20, engaged passive contact 8, winding of relay CO,'batt'ery B to ground, and in multiple therewith through upper contact of relay LR, winding of, coil 11, battery Btto ground, which,

by the opening'of the contacts of T R, interrupts circuit tor'the magnet SSMwhich deenergizes and causes side switch brushes 13 to- 17, inclusive, to be moved from connection with theirrfirst associated contacts from normal to connection with their second and last associated contactsfrom normal.

Assumingthe line calling to be connected with a set of contacts 8 to 10, inclusive, other thanthefirst set, then, owingto the absence of the connection of the winding of coil 11 and battery B therethrough with the con- -tact'8 of such line, the flow of current through the relay TR will not be sufiicient to cause its actuation, with the result'that the ;magnet SSM remains energized and maintains the vibratory circuit for the mag: net VM, which continues to be energized and deenergized until the brush 20 engages the contact '8 connected with a line awaiting selection, when, owing to the energized condition ofthe relay LR and the connection of the winding of resistancell and battery Bfwith the contact 8 of, such line, in multiple with the winding of CO-,suflicient current flows through windingjof relays. TR and- C0 to cause their actuation, whereupon, by the opening of the contacts of TR, circuit for the magnet SSM is interrupted, the magnet deenergized, interrupting circuit for the magnet VM, preventing its further energization, leaving the brushes 18 to'-20,-' inclusive, in connection withtheir associated set of contacts 8 to 10, terminals of a callingline.

The deenergization of magnet SSM causes the side switch brushes 13 to 17, inclusive to be rotated from connection with their asso ciated first contacts from normal to connection with their associated second and last contacts from normal. The disconnection of brush 15 from its second contact from normal interrupts the traced circuit tor'the relay TR, which deenergizes. The

' closure of the brush 15 with its second contact from normal establishes a'maintaining which, by the opening of its contacts, inter rupts the circuit therethrough for the relay LR, which dee'nergizes, interrupting, by the opening of its contacts, circuit for the relay. GBC, which deenerglzes opening 1ts alter nate contact, interrupting the starting circuit for the line finders and interrupting" circuit for the slow-release relays ,23,which det-inergize. The connection of brushes 13 and 14 with their associated. second contacts from normal extends the line of the calling substation to connection with the first selector, whereupon a relay (not; shown) 'is brought into connection with the; line and energized, which acts to. disconnect ground from the conductor Q-tto prevent the establishment of the energizing circuit for the 7 release magnet REL following the ,denergization of. the slow-release relay ,23. Lv

Responsive to the connec ion of brush 15 with its'second contact from normal, ground is connectedwith the multiply connected passive coi'itacts 111 of each of the connector switches tothe' passive contacts of which are connected called terminals of theline, with the result thatshould selection of the line by any" such connectorswitch beattempted,

circuit will be established for the test' rel'ay 126 of such connector from grounded second side switch contact from normal, brush 15 in engagement therewith, brush 20, engaged passive contactS, passive contact 111, brush 127, side switcharm 128, its associated first contact fromfnormal, left-hand winding oi test relay 126, battery B to ground, which will energize the relay and thereby, in a manner (not SllOWH) prevent the selection of the "line by such connector switch;

Following the'eXtension of the line'of the calling"- siibs'tation to thefirst selector, the subscriber, by" operating fl e impulse transmitter' tliereat, may causethe actuation of the firstselector to select an idle trunk of a desired gr-oup leadingto and terminating "in second selector switcher-connector switch, and thereafter, by subsequent a'ctuations of the impulsetransmitter,cause the'operation of such-selected second selector or connectorto select thecalled terminals 111,112,113 of a desired called substation. At time of disconnection, the=conductor 24 is, in" a manner'not shown, connected with ground, and circuit established for the release relay REL which may be traced from grounded conductor 24,1001.- m'al contact of relay 23, off-normal contact ON (closed, responsive to the first energization of magnet RM), winding of'REL, battery B to ground, which energizes and restores the switch to its normal position. The disconnection of brush 15 from its second contact fromnormal or the disconnection ofbru'sh' 20 from the contact 8, interrupts circuit for the relay G0 which deenergizes and, by the closure of its contacts, reestablishes connection of the line relay LR with thedine, whereby another call may be initiated over the'line. Also, by the disconnection of brush 15 from its second contact from normal, ground is d sconnected from the test terminals of the line, whereby the line is rendered'selectable by the connectors. When the brushes of the line finder reach normal position, the contact ON is opened, which interrupts'circuit for the release magnet REL. The connection of brush 16 with its normal contact, when brush 22 reaches normal position, places the line finder 1n position' to be again actuated responsive to the next succeeding call.

What is'claimed is: 1; In" a teleplionesystem',.asubscribers line, comprising a test terminal, a' relay and a source ofcurrent'connect'ed with said ter "11111131, selector switch comprising; a' con- Integers trol relay, means responsive to "initiation of a call over said line'for decreasing there:

plurality of selector switches each compris-' ing one of said terminals, a control relay for each of said switches, means for decreasing the resistance or said connection between said source and each 01" saidterminals to cause actuation of the control relay of any of said switches tocause selection of said line, means including the test" terminal of a selected line to cause actuation ofsaid'first mentioned relay: and to render the line unselectable by a'ny'jof saidswitches."

8; In a teleph'onesyst'em, the combination with a subseribers line, calling' and called test terminals therefor, a relay and asou'rce of current conne'ctedwith said terminals,;a' group of selector switcheseach comprising a calling" one of said terminals, a second group of selectorsw'itches each comprising a called one of said terminals, of'means for increasingthe'potential of said source at said terminals to render the line selectable by any oneoffirst said switches, and means for reducing the potential of said'so'urceat each of said terminals-to render said line unselectable by the remaining switches of said groups.

4L.- In a telephone exchange system, the combination with a subscribers line,'multiply connected calling and called test terminals therefor, a relay and a source of current connected with said terminals, a selector switch adapted to select a calling one of said terminals, a second selector switch adapted to select a called one of said terminals, of means for increasing the potential of said source at said terminalsto render the line selectable by the first said switch, means responsive to selection of said line by thefirst said switch'for reducing-the" p0- tential of said source at said terminals to render theline unselectable by the second said switch. and means responsive" to'se'lection of said llne efiectlve to cause actuation ofsaid relay;

5; In a telephone system, asubscribers' line comprising a test terminal, a relay and a source of current connected with said terminal, a selector switch, a line relay"asso-" ciated with said subscribers line, means'con trolled by said line-relay. to decrease-there sistan'ce of" said c0nnecti0nwbetweei'r said source and terminal upon" the initiation of a call over said line, to cause selection: of

said line by said switch, and a circuit including said terminal for causing the actuation of said first-mentioned relay.

6. In a telephone system, a subscribers line, a plurality of multiply connected test terminals therefor, a relay and a source of ance of said connection between said source H and each of said terminals to cause the actuation of the control relay of any of said swltches upon engagement with the terminals of said line to effect selection of said line, and a circuit including the test terminal of a selected line to cause the actuation of said first-mentioned relay to render the line unselectable by any of said switches.

In witness whereof, I hereunto subscribe my name this 28th day of September A. D.,

BERT G. DUNHAM.

Copies of'this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C. 

